chore: Added CI jobs to check evaluate, collect_env & demo

[fg-mindee]

Following up on #429, this PR introduces the following modifications:

• adds a job to run the evaluate.py script on FUNSD
• adds a job to check the collect_env.py script
• adds a job to check whether we can run the demo
• adds an option to run the evaluation script on the first N samples (the CI job checks it for the 10 first samples)

Any feedback is welcome!

[codecov]

Codecov Report

Merging #456 (d7227f6) into main (b0d554f) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #456   +/-   ##
=======================================
  Coverage   95.86%   95.86%           
=======================================
  Files          96       96           
  Lines        4013     4013           
=======================================
  Hits         3847     3847           
  Misses        166      166           

Flag	Coverage Δ
unittests	95.86% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update b0d554f...d7227f6. Read the comment docs.

[charlesmindee]

Thanks for that!